Semiconductor device and method of manufacturing

ABSTRACT

The present disclosure relates to a method of forming sidewall spacers configured to improve dielectric fill between adjacent gate structures. In some embodiments, the method may be performed by depositing a sidewall spacer material over a first gate structure and a second gate structure. A first etching process is performed on the sidewall spacer material to form a first intermediate sidewall spacer surrounding the first gate structure and a second sidewall spacer surrounding the second gate structure. A masking material is formed over the substrate. Parts of the first intermediate sidewall spacer protrude outward from the masking material, while the second sidewall spacer is completely covered by the masking material. A second etching process is then performed on the parts of the first intermediate sidewall spacer protruding outward from the masking material to form a first sidewall spacer recessed below an uppermost surface of the first gate structure.

REFERENCE TO RELATED APPLICATION

This Application claims priority to U.S. Provisional Application No.62/539,601 filed on Aug. 1, 2017, the contents of which are herebyincorporated by reference in their entirety.

BACKGROUND

To improve the functionality of integrated chips, the semiconductorindustry has continually increased the number of transistors that are onan integrated chip. To achieve a larger number of transistors on anintegrated chip, without substantially increasing a size of theintegrated chip, the semiconductor industry has had to also continuallyreduce the minimum feature size of integrated chip components. Forexample, the minimum gate width of a transistor has been reduced fromtens of microns in the 1980s to tens of nanometers advanced technologynodes (e.g., in 22 nm nodes, 16 nm nodes, etc.).

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a cross-sectional view of some embodiments of anintegrated chip having sidewall spacers configured to improve dielectricfill between adjacent gate structures.

FIG. 2 illustrates a cross-sectional view of some additional embodimentsof an integrated chip having sidewall spacers configured to improvedielectric fill between adjacent gate structures.

FIGS. 3A-3B illustrate some additional embodiments of an integrated chiphaving sidewall spacers configured to improve dielectric fill betweenadjacent gate structures.

FIGS. 4-10 illustrate some embodiments of cross-sectional views showinga method of forming an integrated chip having sidewall spacersconfigured to improve dielectric fill between adjacent gate structures.

FIG. 11 illustrate some embodiments of a flow diagram of a method offorming an integrated chip having sidewall spacers configured to improvedielectric fill between adjacent gate structures.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

In recent years, the continual reduction of integrated chip minimumfeature sizes has made many processes of semiconductor fabrication moredifficult. For example, as a minimum gate pitch has decreased the spacebetween adjacent gate structures has also decreased. In many modern dayintegrated chips the space between adjacent gate structures hasdecreased so that it is smaller than heights of the gate structures,resulting in a high aspect ratio trench between the adjacent gatestructures. The high aspect ratio trench is difficult to fill with adielectric material without generating defects (e.g., voids) in thedielectric material.

Such defects can have a detrimental effect on integrated chips. Forexample, to form a conductive contact on source/drain regions, thedielectric material between adjacent gate structures is etched to form acontact hole, and a conductive material is formed within the contacthole. However, if voids are present in the dielectric material, thevoids may be filled with the conductive material during formation of theconductive contacts. If the voids are filled with the conductivematerial, a distance between the conductive material and the surroundinggate structures is reduced. Reducing a distance between the conductivematerial and the surrounding gate structures reduces a thickness of thedielectric material between the conductive material and the gatestructures and therefore can lead to a higher rate of time dependentdielectric breakdown (TDDB) and device failure.

The present disclosure, in various embodiments, relates to a method offorming sidewall spacers configured to improve dielectric fill betweenadjacent gate structures, and an associated apparatus. In someembodiments, the method comprises depositing a sidewall spacer materialover a first and second plurality of gate structures. A first etchingprocess is performed on the sidewall spacer material to form a firstplurality of intermediate sidewall spacers surrounding the firstplurality of gate structures and a second plurality of sidewall spacerssurrounding the second plurality of gate structures. A masking materialis formed over the substrate. Parts of the first plurality ofintermediate sidewall spacers protrude outward from the maskingmaterial, while the second plurality of sidewall spacers are completelycovered by the masking material. A second etching process is thenperformed on the parts of the first plurality of intermediate sidewallspacers protruding outward from the masking material to form a firstplurality of sidewall spacers recessed below uppermost surfaces of thefirst plurality of gate structures. Recessing the first plurality ofsidewall spacers below uppermost surfaces of the first plurality of gatestructures makes it easier to form a dielectric material betweenadjacent ones of the first plurality of gate structures without formingdefects in the dielectric material.

FIG. 1 illustrates a cross-sectional view of some embodiments of anintegrated chip 100 having sidewall spacers configured to improvedielectric fill between adjacent gate structures.

The integrated chip 100 comprises a first plurality of gate structures104 and a second plurality of gate structures 110 arranged over asubstrate 102. The first plurality of gate structures 104 have a firstheight 108 extending between the substrate 102 and uppermost surfaces104 u of the first plurality of gate structures 104. The secondplurality of gate structures have a second height 114 extending betweenthe substrate 102 and uppermost surfaces 110 u of the second pluralityof gate structures 110. The second height 114 is smaller than the firstheight 108. Because the second height 114 is smaller than the firstheight 108, uppermost surfaces 110 u of the second plurality of gatestructures 110 are separated from the substrate 102 by a smallerdistance than uppermost surfaces 104 u of the first plurality of gatestructures 104.

The first plurality of gate structures 104 are surrounded by a firstplurality of sidewall spacers 106 having outermost sidewalls that arelaterally separated from one another. In some embodiments, the firstplurality of sidewall spacers 106 contact sidewalls of the firstplurality of gate structures 104. The first plurality of sidewallspacers 106 extend along sides of the first plurality of gate structures104 to a height that is recessed below the uppermost surfaces 104 u ofthe first plurality of gate structures 104 by a first distance 124. Insome embodiments, tops of the first plurality of sidewall spacers 106are arranged along one or more horizontal planes 125 that are verticallybetween the uppermost surfaces 104 u of the first plurality of gatestructures 104 and the uppermost surfaces 110 u of the second pluralityof gate structures 110. For example, the one or more horizontal planes125 may be the first distance 124 below the uppermost surfaces 104 u ofthe first plurality of gate structures 104 and a second distance 126above the uppermost surfaces 110 u of the second plurality of gatestructures 110.

The second plurality of gate structures 110 are surrounded by a secondplurality of sidewall spacers 112 that are laterally separated from oneanother. In some embodiments, the second plurality of sidewall spacers112 contact sidewalls of the second plurality of gate structures 110.The second plurality of sidewall spacers 112 are recessed belowuppermost surfaces 110 u of the second plurality of gate structures 110by a second distance that is smaller than the first distance 124. Insome embodiments, the second plurality of sidewall spacers 112 arerecessed below uppermost surfaces 110 u of the second plurality of gatestructures 110 by a second distance that is approximately equal to zero.In such embodiments, the second plurality of sidewall spacers 112 extendalong sides of the second plurality of gate structures 110 to a heightthat is substantially equal the second height 114 of the secondplurality of gate structures 110.

A dielectric structure is arranged over the substrate 102. Thedielectric structure comprises a first inter-level dielectric (ILD)layer 116 over the substrate 102 and a second ILD layer 120 over thefirst ILD layer 116. The first ILD layer 116 surrounds the firstplurality of gate structures 104 and the second plurality of gatestructures 110, while the second ILD layer 120 surrounds a plurality ofmetal interconnect wires 122. In some embodiments, conductive contacts118 extend through the first ILD layer 116, from the plurality of metalinterconnect wires 122 to source/drain regions 128 between adjacent onesof the first plurality of gate structures 104 and between adjacent onesof the second plurality of gate structures 110.

Because the first plurality of sidewall spacers 106 are recessed belowuppermost surfaces 104 u of the first plurality of gate structures 104,the first ILD layer 116 is able to fill areas between adjacent ones ofthe first plurality of gate structures 104 while mitigating voidformation within the first ILD layer 116. Mitigating void formationwithin the first ILD layer 116 improves electrical isolation between theconductive contacts 118 and the first plurality of gate structures 104and therefore improves reliability (e.g., mitigates TDDB) of theintegrated chip 100.

FIG. 2 illustrates a cross-sectional view of some additional embodimentsof an integrated chip 200 having sidewall spacers configured to improvedielectric fill between adjacent gate structures.

The integrated chip 200 comprises a first plurality of gate structures104 and a second plurality of gate structures 110 arranged over asubstrate 102. The first plurality of gate structures 104 and the secondplurality of gate structures 110 are arranged over channel regions 130extending between source/drain regions 128 within the substrate 102. Thefirst plurality of gate structures 104 may have a first height and thesecond plurality of gate structures 110 may have a smaller, secondheight. In some embodiments, the first plurality of gate structures 104may comprise flash memory gate structures arranged within an embeddedmemory region 103 of the substrate 102 and the second plurality of gatestructures 110 may comprise logic gate structures arranged within alogic region 109 of the substrate 102.

In such embodiments, the first plurality of gate structures 104 comprisea tunnel dielectric 202 over the substrate 102, a floating gateelectrode 204 separated from the substrate 102 by the tunnel dielectric202, an inter-electrode dielectric 206 over the floating gate electrode204, and a control gate electrode 208 over the inter-electrodedielectric 206. Because the floating gate electrode 204 is electricallyisolated from an underlying one of the channel regions 130 by the tunneldielectric 202, charges may be trapped on it. The trapped charges areindicative of a data state stored by the floating gate electrode 204.For example, in order to read a memory cell, a voltage is applied to thecontrol gate electrode 208. Since a conductivity of the underlying oneof the channel regions 130 is influenced by charges on the floating gateelectrode 204, a current flow through the channel region can be measuredand used to determine a stored data state.

In some embodiments, the tunnel dielectric 202 may comprise a dielectricmaterial such as an oxide (e.g., silicon dioxide), a nitride, or thelike. In some embodiments, the floating gate electrode 204 and thecontrol gate electrode 208 may comprise polysilicon or the like. In someembodiments, the inter-electrode dielectric 206 may comprise a stackedlayer comprising a nitride layer disposed between oxide layers (i.e., an‘ONO’ layer). In other embodiments, the inter-electrode dielectric 206may comprise a different stacked layers, such as silicon dots arrangedbetween dielectric layers, or the like.

A first plurality of sidewall spacers 106 are disposed along sides ofthe first plurality of gate structures 104. The first plurality ofsidewall spacers 106 are recessed below uppermost surfaces of the firstplurality of gate structures 104 by a first distance 124. In someembodiments, the first distance 124 may be in a range of betweenapproximately 5 nanometers (nm) and approximately 25 nm. In someadditional embodiments, the first distance 124 may be in a range ofbetween approximately 10 nm and approximately 20 nm. In someembodiments, the first plurality of sidewall spacers 106 extend alongthe first plurality of gate structures 104 to positions betweenuppermost surfaces of the inter-electrode dielectric 206 and the controlgate electrode 208, so that the control gate electrode 208 protrudesoutward from between interior sidewalls of the first plurality ofsidewall spacers 106.

The second plurality of gate structures 110 comprise a gate dielectric210 arranged over the substrate 102 and a gate electrode 212 separatedfrom the substrate 102 by the gate dielectric 210. A second plurality ofsidewall spacers 112 are arranged along the second plurality of gatestructures 110. In some embodiments, the second plurality of sidewallspacers 112 extend along the second plurality of gate structures 110 topositions substantially aligned with uppermost surfaces of the gateelectrode 212. In some embodiments, the gate electrode 212 may comprisepolysilicon and the gate dielectric 210 may comprise a dielectric (e.g.,an oxide, a nitride, or the like). In other embodiments, the gateelectrode 212 may comprise a metal (e.g., aluminum, platinum, ruthenium,or the like.) and the gate dielectric 210 may comprise a high-kdielectric material (e.g., hafnium dioxide (HfO₂), zirconium dioxide(ZrO₂) and titanium dioxide (TiO₂), or the like). In some embodiments,the first and second plurality of sidewall spacers, 106 and 112, maycomprise a same material. For example, the first and second plurality ofsidewall spacers, 106 and 112, may comprise an oxide (e.g., silicondioxide, etc.), a nitride (e.g., silicon nitride, silicon oxy-nitride,etc.), or the like.

A contact etch stop layer (CESL) 214 is disposed over the substrate 102,and a first inter-level dielectric (ILD) layer 116 is over the CESL 214.In some embodiments, the CESL 214 contacts sidewalls of the firstplurality of gate structures 104 and the first plurality of sidewallspacers 106. A plurality of conductive contacts 118 a-118 c are arrangedwithin the first ILD layer 116. The plurality of conductive contacts 118a-118 c comprise first conductive contacts 118 a that extend to thecontrol gate electrodes 208 and second conductive contacts 118 b thatextend to the gate electrodes 212. The plurality of conductive contacts118 a-118 c further comprise third conductive contacts 118 c that extendbetween adjacent ones of the first plurality of gate structures 104 andbetween adjacent ones of the second plurality of gate structures 110 tothe source/drain regions 128 within the substrate 102. An additionaletch stop layer 216 separates the first ILD layer 116 from a second ILDlayer 120 over the first ILD layer 116. One or more metal interconnectwires 122 are arranged within the second ILD layer 120.

Although FIG. 2 illustrates the first plurality of gate structures 104and the second plurality of gate structures 110 as having a specifiedlayers and/or shapes, it will be appreciated that the first plurality ofgate structures 104 and the second plurality of gate structures 110 arenot limited to the structures illustrated in FIG. 2. Rather, inalternative embodiments, the first plurality of gate structures 104 andthe second plurality of gate structures 110 may have different shapesand/or may have additional layers or fewer layers. For example, in someembodiments, the first plurality of gate structures 104 and the secondplurality of gate structures 110 may both be logic gate structureshaving different heights due to different thicknesses of the gatedielectric layers, gate electrodes, and/or hard masks (e.g., the firstplurality of gate structures 104 may be associated with high voltagetransistors and the second plurality of gate structures 110 may beassociated with lower voltage transistors that have thinner gatedielectrics).

FIGS. 3A-3B illustrate some additional embodiments of an integrated chiphaving sidewall spacers configured to improve dielectric fill betweenadjacent gate structures.

As shown in cross-sectional view 300 of FIG. 3A, the integrated chipcomprises a first plurality of gate structures 104 having a first heightand a second plurality of gate structures 110 having a second heightless than the first height.

A first plurality of sidewall spacers 302 (e.g., corresponding to thefirst plurality of sidewall spacers 106) surround the first plurality ofgate structures 104, and a second plurality of sidewall spacers 304(e.g., corresponding to the second plurality of sidewall spacers 112)surround the second plurality of gate structures 110. In someembodiments, the first plurality of sidewall spacers 302 may have afirst lower region 302 a and a first upper region 302 b over the firstlower region 302 a. The second plurality of sidewall spacers 304 mayhave a second lower region 304 a and a second upper region 304 b overthe second lower region 304 a. The first upper region 302 b and thesecond upper region 304 b have angled outer sidewalls that respectivelycause widths of the first plurality of sidewall spacers 302 and thesecond plurality of sidewall spacers 304 to monotonically decrease overheights of the first upper region 302 b and the second upper region 304b, respectively.

The first lower region 302 a and the first upper region 302 b meet alonga horizontal plane 303 that is over uppermost surfaces of the secondplurality of gate structures 110. In some embodiments, the sidewalls ofthe first lower region 302 a and the first upper region 302 b may beconnected by a ledge 306. In other embodiments, the sidewalls of thefirst lower region 302 a and the first upper region 302 b may bedirectly connected.

The first plurality of sidewall spacers 302 have a first cross-sectionalprofile that has a different shape and size than a secondcross-sectional profile of the second plurality of sidewall spacers 304.For example, in some embodiments, a first line 308 extending betweenends of a sidewall of the first upper region 302 b may have a firstslope that is larger than a slope of a second line 310 extending betweenends of a sidewall of the second upper region 304 b. In someembodiments, an angular difference θ between the first line 308 and ahorizontal line may be in a range of between approximately 55° andapproximately 65°, while an angular difference Φ between the second line310 and a horizontal line may be in a range of between approximately 45°and approximately 50°. In some additional embodiments, a sidewall of thefirst upper region 302 b has a smaller curvature than a sidewall of thesecond upper region 304 b. For example, the sidewall of the first upperregion 302 b has a first deviation from the first line 308 that issmaller than a second deviation of the sidewall of the second upperregion 304 b from the second line 310.

In some embodiments, the sidewall of the first upper region 302 b has alinear segment extending along a non-zero distance of the sidewall. Thelinear segment and relatively large slope of the sidewall of the firstupper region 302 b causes the first plurality of sidewall spacers 302 todefine an opening comprising a ‘V’ shape between adjacent ones of thefirst plurality of gate structures 104. The ‘V’ shape of the openingreduces an aspect ratio of a gap between adjacent ones of the firstplurality of sidewall spacers 302, and therefore gives the firstplurality of sidewall spacers 302 a geometry that enables easier fillingof the gap.

In some embodiments, the first upper region 302 b has a height (in adirection perpendicular to an upper surface of the substrate 102) thatis larger than a height of the second upper region 304 b. In someembodiments, the height of the first upper region 302 b is a largerportion of a height of the first plurality of sidewall spacers 302 thanthe height of the second upper region 304 b is a portion of a height ofthe second plurality of sidewall spacers 304. For example, in someembodiments, the height of the first upper region 302 b is betweenapproximately 20% and approximately 35% of a height of the firstplurality of sidewall spacers 302, while the height of the second upperregion 304 b is between approximately 10% and approximately 20% of aheight of the second plurality of sidewall spacers 304.

In some embodiment, a first hard mask 312 may be arranged along tops ofthe first plurality of gate structures 104, and a second hard mask 314may be arranged along tops of the second plurality of gate structures110. In such embodiments, a first conductive contact 118 a is configuredto extend through the first hard mask 312 to the control gate electrode208 and a second conductive contact 118 b is configured to extendthrough the second hard mask 314 to the control gate electrode 208. Insome embodiments, the first hard mask 312 and the second hard mask 314may comprise a nitride (e.g., silicon nitride, tantalum oxy-nitride,etc.), an oxide (e.g., silicon oxide, silicon oxy-nitride, etc.), ametal (e.g., titanium, titanium nitride, etc.), or the like.

FIG. 3B illustrates a top-view 316 of the integrated chip shown in FIG.3A along line A-A″. As shown in top-view 316, in some embodiments, thefirst plurality of gate structures 104 may be oriented along a firstdirection 318 and separated from one another along a second direction320 that is perpendicular to the first direction 318. The floating gateelectrodes 204 within the first plurality of gate structures 104 extendin the first direction 318 over multiple source/drain regions 128. Insome embodiments, the source/drain regions 128 are configured to act asbit-lines while control gate electrodes (208 of FIG. 3A) overlying thefloating gate electrodes 204 are configured to act as word-lines. Byorienting the first plurality of gate structures 104 along a samedirection, lithography techniques can be optimized to result in asmaller distance between adjacent ones of the first plurality of gatestructures 104. In some embodiments (not shown), the second plurality ofgate structures (110 of FIG. 3A) may be oriented along the firstdirection 318 also, while in other embodiments the second plurality ofgate structures (110 of FIG. 3A) may be oriented along the seconddirection 320.

FIGS. 4-10 illustrate some embodiments of cross-sectional views 400-1000showing a method of forming an integrated chip having sidewall spacersconfigured to improve dielectric fill between adjacent gate structures.Although the cross-sectional views 400-1000 shown in FIGS. 4-10 aredescribed with reference to a method, it will be appreciated that thestructures shown in FIGS. 4-10 are not limited to the method but rathermay stand alone separate of the method.

As shown in cross-sectional view 400 of FIG. 4, a first plurality ofgate structures 104 having a first height 108 and a second plurality ofgate structures 110 having a second height 114 are formed over asubstrate 102. In various embodiments, the substrate 102 may be any typeof semiconductor body (e.g., silicon, SiGe, SOI, etc.), such as asemiconductor wafer and/or one or more die on a wafer, as well as anyother type of semiconductor and/or epitaxial layers, associatedtherewith.

In some embodiments, the first plurality of gate structures 104 and thesecond plurality of gate structures 110 may be formed by separatefabrication processes (e.g., depositions, thermal growth processes,and/or patterning processes). For example, in some embodiments, a firstmasking layer may be formed over a first region 402 (e.g., correspondingto embedded memory region 103 of FIG. 2) of the substrate 102. A tunneldielectric film may be subsequently be formed over the substrate 102, afloating gate electrode film may be formed over the tunnel dielectricfilm, an inter-electrode dielectric film may be formed over the floatinggate electrode film, and a control gate electrode film may be formedover the inter-electrode dielectric film. A first patterning process isthen performed, which patterns the tunnel dielectric film, the floatinggate electrode film, the inter-electrode dielectric film, and thecontrol gate electrode film to form a tunnel dielectric 202, a floatinggate electrode 204, an inter-electrode dielectric 206, and a controlgate electrode 208. In some embodiments, the first patterning processmay be performed according to a first hard mask (not shown) formed overthe control gate electrode film.

After the first patterning process is completed, the first masking layeris removed and a second masking layer is formed over a second region 404(e.g., corresponding to logic region 109 of FIG. 2) of the substrate102. A gate dielectric film may be subsequently be formed over thesubstrate 102 and a gate electrode film may be formed over the gatedielectric film. A second patterning process is performed, whichpatterns the gate dielectric film and the gate electrode film to form agate dielectric 210 and a gate electrode 212. In some embodiments, thesecond patterning process may be performed according to a second hardmask (not shown) formed over the gate electrode film.

As shown in cross-sectional view 500 of FIG. 5, a sidewall spacermaterial 502 is formed over the first plurality of gate structures 104and the second plurality of gate structures 110. The sidewall spacermaterial 502 continually extends between adjacent ones of the firstplurality of gate structures 104 and/or the second plurality of gatestructures 110. In some embodiments, the sidewall spacer material 502may comprise a dielectric material, such as an oxide and/or a nitride(e.g., silicon dioxide, silicon nitride, silicon oxy-nitride, or thelike.). In some embodiments, the sidewall spacer material 502 may beformed by way of a deposition technique (e.g., a chemical vapordeposition (CVD), a physical vapor deposition, a plasma enhanced CVD,etc.).

As shown in cross-sectional view 600 of FIG. 6, a first etching processis performed on the sidewall spacer material (502 of FIG. 5) toconcurrently form a first plurality of intermediate sidewall spacers 604and a second plurality of sidewall spacers 112. The first etchingprocess is performed by exposing the sidewall spacer material (502 ofFIG. 5) to a first etchant 602. The first etchant 602 removes thesidewall spacer material from horizontal surfaces of the substrate 102,the first plurality of gate structures 104, and the second plurality ofgate structures 110. In some embodiments, the first etchant 602 maycomprise a dry etchant, such as a plasma etchant (e.g., a reactive ionetchant) or an ion bombardment etchant. In other embodiments, the firstetchant 602 may comprise a wet etchant (e.g., hydrofluoric acid (HF),Tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH), or thelike). The first plurality of intermediate sidewall spacers 604 comprisediscrete structures arranged along opposing sides of the first pluralityof gate structures 104. The second plurality of sidewall spacers 112comprise discrete structures arranged along opposing sides of the secondplurality of gate structures 110.

In some embodiments, the first etching process may over-etch thesidewall spacer material (502 of FIG. 5) resulting in depressions (notshown) within the substrate 102 at locations between adjacent ones ofthe first plurality of gate structures 104 and/or the second pluralityof gate structures 110. For example, the substrate 102 may be recessedto a depth of between approximately 0 nm and approximately 5 nm betweenadjacent ones of the first plurality of gate structures 104 and betweenadjacent ones of the second plurality of gate structures 110. In suchembodiments, the first plurality of intermediate sidewall spacers 604may be recessed below uppermost surfaces of the first plurality of gatestructures 104 and the second plurality of sidewall spacers 112 may berecessed below uppermost surfaces of the second plurality of gatestructures 110.

As shown in cross-sectional view 700 of FIG. 7, a masking material 702is formed over the substrate 102. The masking material 702 extends to aheight 704 that is less than the first height 108 and that is greaterthan the second height 114. Such a height 704 causes the maskingmaterial 702 to cover a part, but not all, of the first plurality ofintermediate sidewall spacers 604, and to further cover an entirety ofthe second plurality of sidewall spacers 112. For example, in someembodiments, the masking material 702 has an upper surface 702 u thatmay overlie uppermost surfaces of the second plurality of gatestructures 110 by a first distance 706 and be recessed below uppermostsurfaces of the first plurality of gate structures 104 by a seconddistance 708. In some embodiments, the masking material 702 may comprisea photoresist layer. In some embodiments, the photoresist layer may beformed by a spin coating process.

As shown in cross-sectional view 800 of FIG. 8, a second etching processis performed. The second etching process is performed by exposingregions of the first plurality of intermediate sidewall spacers (604 ofFIG. 7), which are not covered by the masking material 702, to a secondetchant 802. The second etchant 802 etches the first plurality ofintermediate sidewall spacers to form a first plurality of sidewallspacers 106 having a height less than the first plurality ofintermediate sidewall spacers. The first plurality of sidewall spacers106 are recessed below uppermost surfaces 104 u of the first pluralityof gate structures 104 by a first distance 124 that is greater than adistance which the second plurality of sidewall spacers 112 are recessedbelow uppermost surfaces 110 u of the second plurality of gatestructures 110.

The second etchant 802 also changes a cross-sectional profile of thefirst plurality of intermediate sidewall spacers so that the firstplurality of sidewall spacers 106 have a cross-sectional profile with adifferent shape and size than the first plurality of intermediatesidewall spacers. In some embodiments, the second etchant 802 reduces acurvature of the first plurality of intermediate sidewall spacers sothat the first plurality of sidewall spacers 106 have sidewalls over themasking material 702 that are more linear than sidewalls of the firstplurality of intermediate sidewall spacers over the masking material702. In some embodiments, the second etchant 802 may comprise a dryetchant (e.g., a plasma etchant, an ion bombardment etchant) and/or awet etchant (e.g., TMAH, KOH, or the like). After the second etchingprocess is completed, the masking material 702 is removed.

As shown in cross-sectional view 900 of FIG. 9, source/drain regions 128are formed within the substrate 102 between adjacent ones of the firstplurality of gate structures 104 and between adjacent ones of the secondplurality of gate structures 110. In some embodiments, the source/drainregions 128 may be formed by selectively implanting a dopant species 902into the substrate 102. In some embodiments, the dopant species 902 maybe selectively implanted into the substrate 102 according to a maskcomprising a masking layer 904 (e.g., a photoresist layer). In variousembodiments, the dopant species 902 may comprise a p-type dopant (e.g.,boron, gallium, or the like) or an n-type dopant (e.g., phosphorus,arsenic, or the like). In some embodiments, after implanting the dopantspecies 902 into the substrate 102, a drive-in anneal may be performedto diffuse the dopant species within the substrate 102.

As shown in cross-sectional view 1000 of FIG. 10, one or moreinterconnect layers, 118 and 122, are formed within ILD layers, 116 and120, over the substrate 102. The one or more interconnect layers, 118and 122, comprise a plurality of conductive contacts 118 a-118 c formedwithin a first ILD layer 116 over the substrate 102 and a plurality ofmetal interconnect wires 122 arranged within a second ILD layer 120 overthe first ILD layer 116. The plurality of conductive contacts 118 a-118c comprise first conductive contacts 118 a extending between the controlgate electrodes 208 and the plurality of metal interconnect wires 122and second conductive contacts 118 b extending between the gateelectrodes 212 and the plurality of metal interconnect wires 122. Theplurality of conductive contacts 118 a-118 c further comprise thirdconductive contacts 118 c that extend between adjacent ones of the firstplurality of gate structures 104 and between adjacent ones of the secondplurality of gate structures 110 to the source/drain regions 128 withinthe substrate 102.

In some embodiments, the one or more interconnect layers, 118 and 122,may be formed using a damascene process (e.g., a single damasceneprocess or a dual damascene process). The damascene process is performedby forming an ILD layer over the substrate 102, etching the ILD layer toform a hole and/or a trench, and filling the hole and/or trench with aconductive material. In some embodiments, the ILD layer may be depositedby a vapor deposition technique (e.g., PVD, CVD, PE-CVD, ALD, etc.) andthe conductive material may be formed using a deposition process and/ora plating process (e.g., electroplating, electro-less plating, etc.). Invarious embodiments, the one or more interconnect layers, 118 and 122,may comprise tungsten, copper, or aluminum copper, or the like.

FIG. 11 illustrate some embodiments of a flow diagram of a method 1100of forming an integrated chip having sidewall spacers configured toimprove dielectric fill between adjacent gate structures.

While method 1100 is illustrated and described herein as a series ofacts or events, it will be appreciated that the illustrated ordering ofsuch acts or events are not to be interpreted in a limiting sense. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein. In addition, not all illustrated acts may be required toimplement one or more aspects or embodiments of the description herein.Further, one or more of the acts depicted herein may be carried out inone or more separate acts and/or phases.

At 1102, a first plurality of gate structures having first height andsecond plurality of gate structures having second heights are formedover a substrate. In some embodiments, the first plurality of gatestructures and the second plurality of gate structures may be formed bydifferent deposition and/or patterning processes. FIG. 4 illustrates across-sectional view 400 of some embodiments corresponding to act 1102.

At 1104, a spacer material is formed over the first plurality of gatestructures and the second plurality of gate structures. FIG. 5illustrates a cross-sectional view 500 of some embodiments correspondingto act 1104.

At 1106, a first etching process is performed on the spacer material toform first intermediate sidewall spacers surrounding the first pluralityof gate structures and second sidewall spacers surrounding the secondplurality of gate structures. FIG. 6 illustrates a cross-sectional view600 of some embodiments corresponding to act 1106.

At 1108, a masking material is formed over the substrate. The maskingmaterial has an upper surface below uppermost surfaces of the firstplurality of gate structures and above uppermost surfaces of the secondplurality of gate structures. FIG. 7 illustrates a cross-sectional view700 of some embodiments corresponding to act 1108.

At 1110, a second etching process is performed to etch back the firstintermediate sidewall spacers surrounding the first plurality of gatestructures. Etching back the first intermediate sidewall spacers formsfirst sidewall spacers surrounding the first plurality of gatestructures. FIG. 8 illustrates a cross-sectional view 800 of someembodiments corresponding to act 1110.

At 1112, source/drain regions are formed within the substrate. FIG. 9illustrates a cross-sectional view 900 of some embodiments correspondingto act 1112.

At 1114, one or more interconnect layers are formed within aninter-level dielectric (ILD) layer over the substrate. FIG. 10illustrates a cross-sectional view 1000 of some embodimentscorresponding to act 1114.

Accordingly, the present disclosure relates to a method of formingsidewall spacers that are configured to improve dielectric fill betweenadjacent gate structures, and an associated apparatus.

In some embodiments, the present disclosure relates to a method offorming an integrated chip. The method includes forming a first gatestructure and a second gate structure over a substrate; forming asidewall spacer material over the first gate structure and over thesecond gate structure; performing a first etching process on thesidewall spacer material to form a first intermediate sidewall spacersurrounding the first gate structure and to form a second sidewallspacer surrounding the second gate structure; forming a masking materialover the substrate, a part of the first intermediate sidewall spacerprotrudes outward from the masking material and the second sidewallspacer is completely covered by the masking material; and performing asecond etching process on the part of the first intermediate sidewallspacer that protrudes outward from the masking material to form a firstsidewall spacer recessed below a first uppermost surface of the firstgate structure. In some embodiments, a top of the first sidewall spaceris arranged along a horizontal plane between the first uppermost surfaceand a second uppermost surface of the second gate structure. In someembodiments, the first sidewall spacer has a first cross-sectionalprofile that is a different shape and size than a second cross-sectionalprofile of the second sidewall spacer. In some embodiments, the firstsidewall spacer has a first lower region and a first upper region thathas a first angled sidewall that causes a width of the first sidewallspacer to monotonically decrease; and the second sidewall spacer hassecond lower region and a second upper region that has a second angledsidewall that causes a width of the second sidewall spacer tomonotonically decrease. In some embodiments, the first sidewall spacerhas a ledge extending between the first lower region and the first upperregion. In some embodiments, the method further includes forming acontact etch stop layer over the substrate, the contact etch stop layeris separated from the first gate structure by the first sidewall spacerand further separated from the second gate structure by the secondsidewall spacer. In some embodiments, the contact etch stop layercontacts sidewalls of the first sidewall spacer and sidewalls of thefirst gate structure. In some embodiments, the first gate structure andthe second gate structure are formed by different deposition andpatterning processes. In some embodiments, the first sidewall spacer isrecessed below the first uppermost surface by a distance in a range ofbetween approximately 10 nm and approximately 20 nm.

In other embodiments, the present disclosure relates to a method offorming an integrated chip. The method includes depositing a sidewallspacer material over a first plurality of gate structures and over asecond plurality of gate structures over a substrate; performing a firstetching process on the sidewall spacer material to form firstintermediate sidewall spacers surrounding the first plurality of gatestructures and to form second sidewall spacers surrounding the secondplurality of gate structures; forming a photoresist layer over thesubstrate, the photoresist layer has an upper surface below tops of thefirst intermediate sidewall spacers and above tops of the secondsidewall spacers; and performing a second etching process, with thephotoresist layer over the substrate, to remove parts of the firstintermediate sidewall spacers and form first sidewall spacers recessedbelow uppermost surfaces of the first plurality of gate structures. Insome embodiments, the method further includes forming a source/drainregion between adjacent ones of the first plurality of gate structures;forming an inter-level dielectric layer between the first sidewallspacers and the second sidewall spacers; etching the inter-leveldielectric layer to form a contact hole over the source/drain region,the contact hole extends between adjacent ones of the first sidewallspacers; and depositing a conductive material within the contact hole.In some embodiments, the first sidewall spacers respectively have aledge extending between a lower sidewall and an overlying uppersidewall. In some embodiments, forming the first plurality of gatestructures includes forming a tunnel dielectric film over the substrate;forming a floating gate electrode film over the tunnel dielectric film;forming an inter-electrode dielectric film over the floating gateelectrode film; forming a control gate electrode film over theinter-electrode dielectric film; and selectively patterning the tunneldielectric film, the floating gate electrode film, the inter-electrodedielectric film, and the control gate electrode film according to afirst etching process. In some embodiments, forming the second pluralityof gate structures includes forming a gate dielectric film over thesubstrate; forming a gate electrode film over the gate dielectric film;and selectively patterning the gate dielectric film and the gateelectrode film according to a second etching process separate from thefirst etching process.

In yet other embodiments, the present disclosure relates to anintegrated chip. The integrated chip includes a first gate structureover a substrate and having a first height between the substrate and afirst uppermost surface of the first gate structure; a second gatestructure over the substrate and having a second height between thesubstrate and a second uppermost surface of the second gate structure,the second height is smaller than the first height; a first sidewallspacer surrounding the first gate structure and recessed below the firstuppermost surface; and a second sidewall spacer surrounding the secondgate structure and having outermost sidewalls separated from outermostsidewalls of the first sidewall spacer, a top of the first sidewallspacer is arranged along a horizontal plane that is between the firstuppermost surface and the second uppermost surface. In some embodiments,second sidewall spacer has a height that is substantially equal to thesecond height. In some embodiments, the first sidewall spacer has afirst cross-sectional profile that has a different shape and size than asecond cross-sectional profile of the second sidewall spacer. In someembodiments, the first sidewall spacer has a first lower region and afirst upper region that has a first angled sidewall that causes a widthof the first sidewall spacer to monotonically decrease; and the secondsidewall spacer has second lower region and a second upper region thathas a second angled sidewall that causes a width of the second sidewallspacer to monotonically decrease. In some embodiments, a first lineextending between ends of the first angled sidewall has a first slopethat is greater than a second slope of a second line extending betweenends of the second angled sidewall. In some embodiments, the first gatestructure comprises a floating gate separated from the substrate by atunnel dielectric and a control gate separated from the floating gate byan inter-level dielectric; and the second gate structure comprises agate electrode separated from the substrate by a gate dielectric.

In yet other embodiments, the present disclosure relates to anintegrated chip. The integrated chip includes a first gate structureover a substrate and having a first uppermost surface; a second gatestructure over the substrate and having a second uppermost surface; anda first sidewall spacer surrounding the first gate structure, a top ofthe first sidewall spacer is arranged along a horizontal plane that isbelow the first uppermost surface and that is above the second uppermostsurface. In some embodiments, the integrated chip further includes asecond sidewall spacer surrounding the second gate structure andextending to the second uppermost surface, the first sidewall spacer hasoutermost sidewalls separated from outermost sidewalls of the secondsidewall spacer. In some embodiments, the integrated chip furtherincludes a second sidewall spacer surrounding the second gate structure,the first sidewall spacer has a top that is recessed below the firstuppermost surface by a first distance and the second sidewall spacer hasa top that is recessed below the second uppermost surface by a seconddistance smaller than the first distance. In some embodiments, thesecond distance is substantially equal to zero. In some embodiments, thefirst sidewall spacer has a first lower region and a first upper regionhaving a first angled sidewall that causes a width of the first sidewallspacer to monotonically decrease; and the second sidewall spacer hassecond lower region and a second upper region having a second angledsidewall that causes a width of the second sidewall spacer tomonotonically decrease. In some embodiments, the first sidewall spacerhas a ledge extending between the first lower region and the first upperregion. In some embodiments, the first gate structure comprises apolysilicon floating gate electrode separated from the substrate by atunnel dielectric and a polysilicon control gate electrode separatedfrom the polysilicon floating gate electrode by an inter-leveldielectric; and the second gate structure comprises a metal gateelectrode separated from the substrate by a gate dielectric. In someembodiments, the polysilicon control gate electrode of the first gatestructure protrudes outward from between interior sidewalls of the firstsidewall spacer. In some embodiments, the first sidewall spacer isrecessed below the first uppermost surface by a distance in a range ofbetween approximately 5 nm and approximately 25 nm. In some embodiments,the integrated chip further includes a contact etch stop layer separatedfrom the first gate structure by the first sidewall spacer. In someembodiments, the contact etch stop layer contacts sidewalls of the firstsidewall spacer and sidewalls of the first gate structure.

In yet other embodiments, the present disclosure relates to anintegrated chip. The integrated chip includes a first gate structureover a substrate and having a first uppermost surface; a first sidewallspacer having a first lower region and a first upper region surroundingthe first gate structure, a top of the first sidewall spacer is arrangedalong a horizontal plane that is below the first uppermost surface; andthe first upper region has a first angled sidewall that causes a widthof the first sidewall spacer to monotonically decrease as a height ofthe first upper region increases. In some embodiments, the firstsidewall spacer has a ledge extending between the first lower region andthe first upper region. In some embodiments, the integrated chip furtherincludes a second gate structure over the substrate and having a seconduppermost surface, wherein the horizontal plane is above the seconduppermost surface. In some embodiments, the first gate structurecomprises a floating gate separated from the substrate by a tunneldielectric and a control gate separated from the floating gate by aninter-level dielectric. In some embodiments, the first angled sidewallhas a linear segment.

In other embodiments, the present disclosure relates to a method offorming an integrated chip. The method includes forming a first gatestructure over a substrate; depositing a sidewall spacer material overthe first gate structure; performing a first etching process on thesidewall spacer material to form a first intermediate sidewall spacersurrounding the first gate structure; forming a masking material overthe substrate, a part of the first intermediate sidewall spacerprotrudes outward from the masking material to a location over themasking material; and performing a second etching process on the part ofthe first intermediate sidewall spacer that protrudes from the maskingmaterial to form a first sidewall spacer recessed below a firstuppermost surface of the first gate structure. In some embodiments, thesecond etching process changes a curvature of a sidewall of the firstintermediate sidewall spacer, so that the first intermediate sidewallspacer has a second cross-sectional profile with a different shape andsize than a first cross-sectional profile of the first sidewall spacer.In some embodiments, the method further includes forming a second gatestructure over the substrate; depositing the sidewall spacer materialover the second gate structure; performing the first etching process onthe sidewall spacer material to form a second sidewall spacersurrounding the second gate structure; and forming the masking materialover a top of the second sidewall spacer. In some embodiments, a top ofthe first sidewall spacer is arranged along a horizontal plane betweenthe first uppermost surface and a second uppermost surface of the secondgate structure.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of forming an integrated chip,comprising: forming a first gate structure and a second gate structureover a substrate; forming a sidewall spacer material over the first gatestructure and over the second gate structure; performing a first etchingprocess on the sidewall spacer material to form a first intermediatesidewall spacer surrounding the first gate structure and to form asecond sidewall spacer surrounding the second gate structure; forming amasking material over the substrate, wherein a part of the firstintermediate sidewall spacer protrudes outward from the masking materialand the second sidewall spacer is completely covered by the maskingmaterial; and performing a second etching process on the part of thefirst intermediate sidewall spacer that protrudes outward from themasking material to form a first sidewall spacer recessed below a firstuppermost surface of the first gate structure.
 2. The method of claim 1,wherein a top of the first sidewall spacer is arranged along ahorizontal plane between the first uppermost surface and a seconduppermost surface of the second gate structure.
 3. The method of claim1, wherein the first sidewall spacer has a first cross-sectional profilethat is a different shape and size than a second cross-sectional profileof the second sidewall spacer.
 4. The method of claim 1, wherein thefirst sidewall spacer has a first lower region and a first upper regionthat has a first angled sidewall that causes a width of the firstsidewall spacer to monotonically decrease; and wherein the secondsidewall spacer has second lower region and a second upper region thathas a second angled sidewall that causes a width of the second sidewallspacer to monotonically decrease.
 5. The method of claim 4, wherein thefirst sidewall spacer has a ledge extending between the first lowerregion and the first upper region.
 6. The method of claim 1, furthercomprising: forming a contact etch stop layer over the substrate,wherein the contact etch stop layer is separated from the first gatestructure by the first sidewall spacer and further separated from thesecond gate structure by the second sidewall spacer.
 7. The method ofclaim 6, wherein the contact etch stop layer contacts sidewalls of thefirst sidewall spacer and sidewalls of the first gate structure.
 8. Themethod of claim 1, wherein the first gate structure and the second gatestructure are formed by different deposition and patterning processes.9. The method of claim 1, wherein the first sidewall spacer is recessedbelow the first uppermost surface by a distance in a range of betweenapproximately 10 nm and approximately 20 nm.
 10. A method of forming anintegrated chip, comprising: depositing a sidewall spacer material overa first plurality of gate structures and over a second plurality of gatestructures over a substrate; performing a first etching process on thesidewall spacer material to form first intermediate sidewall spacerssurrounding the first plurality of gate structures and to form secondsidewall spacers surrounding the second plurality of gate structures;forming a photoresist layer over the substrate, wherein the photoresistlayer has an upper surface below tops of the first intermediate sidewallspacers and above tops of the second sidewall spacers; and performing asecond etching process, with the photoresist layer over the substrate,to remove parts of the first intermediate sidewall spacers and formfirst sidewall spacers recessed below uppermost surfaces of the firstplurality of gate structures.
 11. The method of claim 10, furthercomprising: forming a source/drain region between adjacent ones of thefirst plurality of gate structures; forming an inter-level dielectriclayer between the first sidewall spacers and the second sidewallspacers; etching the inter-level dielectric layer to form a contact holeover the source/drain region, wherein the contact hole extends betweenadjacent ones of the first sidewall spacers; and depositing a conductivematerial within the contact hole.
 12. The method of claim 10, whereinthe first sidewall spacers respectively have a ledge extending between alower sidewall and an overlying upper sidewall.
 13. The method of claim10, wherein forming the first plurality of gate structures comprises:forming a tunnel dielectric film over the substrate; forming a floatinggate electrode film over the tunnel dielectric film; forming aninter-electrode dielectric film over the floating gate electrode film;forming a control gate electrode film over the inter-electrodedielectric film; and selectively patterning the tunnel dielectric film,the floating gate electrode film, the inter-electrode dielectric film,and the control gate electrode film according to a third etchingprocess.
 14. The method of claim 13, wherein forming the secondplurality of gate structures comprises: forming a gate dielectric filmover the substrate; forming a gate electrode film over the gatedielectric film; and selectively patterning the gate dielectric film andthe gate electrode film according to a fourth etching process separatefrom the third etching process.
 15. A method of forming an integratedchip, comprising: forming a first gate structure and a second gatestructure over a substrate; forming a dielectric material over the firstgate structure and over the second gate structure; etching thedielectric material to form a first intermediate sidewall spacersurrounding the first gate structure and to form a second sidewallspacer surrounding the second gate structure; forming a masking layerover the substrate, the masking layer laterally surrounding opposingsides of both the first gate structure and the second gate structure;and etching the first intermediate sidewall spacer to form a firstsidewall spacer after forming the masking layer, wherein a top of thefirst sidewall spacer is below a top of the first gate structure. 16.The method of claim 15, further comprising: spin coating a photoresistlayer onto the substrate, wherein the masking layer is the photoresistlayer.
 17. The method of claim 15, wherein the first intermediatesidewall spacer extends from within the masking layer to over themasking layer.
 18. The method of claim 15, wherein the first gatestructure comprises a tunnel dielectric over the substrate, a floatinggate electrode over the tunnel dielectric, an inter-electrode dielectricover the floating gate electrode, and a control gate electrode over theinter-electrode dielectric; and wherein the second gate structurecomprises a gate electrode separated from the substrate by a gatedielectric.
 19. The method of claim 15, wherein the first sidewallspacer has a first height that is greater than a second height of thesecond sidewall spacer.
 20. The method of claim 15, further comprising:removing the masking layer after etching the first intermediate sidewallspacer; and forming a dielectric over the substrate after removing themasking layer, wherein the dielectric laterally surrounds the firstsidewall spacer and the second sidewall spacer.